1. Field of the Invention
The present invention relates to a piezoelectric element used in a piezoelectric actuator such as a piezoelectric vibrator and a liquid ejecting device, a semiconductor recording device, and a pyroelectric infrared detecting device, an ink jet head using the piezoelectric element, and an ink jet recording device having the ink jet head.
2. Description of the Related Art
In a piezoelectric element, generally, a layered piezoelectric body (such as lead zirconate titanate (PZT)) is disposed between two electrodes (referred to as lower electrode and upper electrode in the following description). The piezoelectric body serves to convert mechanical energy into electrical energy or to convert electrical energy into mechanical energy. The piezoelectric element with such a function is used for various devices.
Piezoelectric ceramics such as lead zirconate titanate (PZT) is used as a material of the piezoelectric body. Lead-based piezoelectric ceramics represented by PZT has various excellent characteristics such as a high piezoelectric constant and is used for various electronic components such as a piezoelectric actuator, a pyroelectric infrared detecting device, and a nonvolatile memory device.
As a configuration of a piezoelectric element, JP-A-2001-284671 discloses a diaphragm-type piezoelectric element in which a vibrating plate is formed on a substrate having a pressure chamber hole formed therein so as to cover the pressure chamber hole and a lower electrode, a piezoelectric body, and an upper electrode are formed on the vibrating plate.
For example, JP-A-05-286131 suggests a technology of forming a homogeneous piezoelectric body in a layered structure on the whole surface of a vibrating plate by the use of a film forming method, dividing the piezoelectric body to correspond to individual pressure chambers by the use of a lithography method, and forming independent piezoelectric elements by pressure chambers.
For example, JP-A-2005-210887 suggests a structure in which an upper electrode of a piezoelectric element is drawn and a lead electrode is patterned from a peripheral edge of the upper electrode to the outside of a peripheral wall of a pressure chamber.
However, in the above-mentioned conventional structures, when the upper electrode, the piezoelectric body, and the lower electrode are stacked and a portion (hereinafter, referred to as piezoelectric active region) for substantially generating pressure in the pressure chamber protrudes from the pressure chamber region to the outside of the peripheral wall of the pressure chamber (that is, to the outside of the edge portion of the pressure chamber), the pressure generated from the piezoelectric active region cannot be effectively transmitted to ink, thereby causing the non-uniform pressure generation from the pressure chamber region.
In addition, cracks can occur in the lead electrode at the boundary between the pressure chamber and the peripheral wall. When cracks occur in the lead electrode, the lead electrode may be short-circuited or leak current may flow in the piezoelectric body.